It is possble and not that expensive (unless you need a new paint job as well). If you have a high end frame made from thin tubes, the seat-stay may not be suitable for loading up and the chainstays may be on the short side. Most mid-range road bikes can be used for hostel loads but not full camping ones.
Check out some of the alternatives to panniers such as Carradice saddlebags.

I had this done to a MTB Fork and it turned out great. The frame builder who did it actually used the bosses which are normally attached to the seat stays,for rear rack, for the front fork. He then mitered them to fit the curve of the fork. A lot more surface area than the traditional eyelet w/ no chance of breaking. If you like the bike, it's worth doing. Like someone above said, having it repainted will cost you.